The present invention relates to ophthalmic lenses, compositions useful for inclusion in such lenses, and methods for producing such lenses and compositions. More particularly, the invention relates to polymeric ophthalmic lenses, such as corneal contact lenses and the like, polymeric compositions useful included in ophthalmic lenses and methods for producing such lenses and compositions.
Hydrophilic lenses, such as corneal contact lenses, are often formed from covalently cross-linked polymers based on hydrophilic derivatives of acrylic or methacrylic acid, hydrophilic vinylic monomers such as vinylpyrrolidone, and the like. When hydrated, these hydrophilic cross-linked polymers can be referred to as hydrogels and include relatively large quantities of water without dissolving. Such polymers may include minor amounts of polymeric units derived from less hydrophilic, or even hydrophobic, monomers to confer mechanical strength and other useful properties.
Although conventional hydrophilic polymer or hydrogel lenses are useful and effective, some problems do present themselves, from time to time. For example, conventional hydrophilic contact lenses, particularly after long periods of in-the-eye use, do have a tendency to lose water content. Reduction in water content tends to detrimentally affect the physical structure and/or optical properties of the lens. This reduction in water content can lead to lens wearer discomfort and even to actual irritation or other damage to the eye. In addition, such conventional lenses may lose lubricity or exhibit relatively large amounts of friction with the corneal surface, which also can cause lens wearer discomfort and/or eye irritation and the like. Such reduced lens water content and/or reduced lubricity can result in the lens wearer perceiving that his/her eye is dry. Such “dry eye” phenomenon can be overcome through the use of eye drops and/or lubricants. However, it would be advantageous to reduce or even substantially eliminate these problems without the need for eye drops or separate lubricants.
In short, there is a continued need for enhanced ophthalmic lenses, e.g., corneal contact lenses, enhanced materials of construction for such lenses and enhanced methods for producing such lenses and materials.